I've been doing a bunch of puzzles at chesstempo.com and I noticed because it's timed that I look for the most obvious answer that's never more than a few moves deep. Also, after a while the puzzles become kinda predictable given the pieces available. It seems to me that if I do a lot of puzzles that I'll bring that same shallow thinking to my games.

Is it Chess Tempo or are tactic puzzles overall limited in usefulness?

I think you just need to switch up a little and do puzzles from multiple sources -- though the fact that you're finding them "predictable" could be a sign that your tactical eye is getting sharper. :wink: